Thank you ever so much for your reply - you have been a great help! I have now been able to trace back a reasonable way on both the van den Ijssel and Olie sides.
I am now at a bit of a brick wall on the van den Ijssel side though. I got back to Johannes b.1849, son of Johannes van den Ijssel and Maria Geertruida Jonas. However, I shall keep trying and see if I manage to get a breakthrough!
I have been trying to look into the family for a friend but have been completely stuck - now I can see her tomorrow and give her the surprise! Thank you once again.